coupling vs penetrative sex

coupling

noun
  • Sexual intercourse. 

  • The property of physical systems that they are interacting with each other 

  • Act of joining together to form a couple. 

  • A device that couples two things together. 

  • The degree of reliance between two or more software modules. 

  • A connection between two electronic circuits such that a signal can pass between them. 

penetrative sex

noun
  • Sex in which the penis is inserted into the sexual partner's vagina, rectum or mouth. 

How often have the words coupling and penetrative sex occurred in a corpus of books? (source: Google Ngram Viewer )